A Girdler and a Pruner

Twigs littering the yard under the elm tree mean only one thing — tree girdlers.

Tree girdlers and tree pruners are both species of long horned beetles.

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The female tree girdler lays an egg at the tip of a branch. She then crawls toward the tree’s trunk and cuts a groove. She also makes slits in the bark on each side of the groove. This causes the twig to die, and some fall from the tree.

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Twig pruners overwinter as a pupa inside the largest end of the fallen twig. I rarely find these. This is a twig off sweetgum tree in the yard.

The female lays eggs near the tip of the twig. The larva burrows into the twig, toward the tree’s trunk until it reaches where the twig measures 1/2 – 1 inch in diameter. Here it stops and starts cutting in a spiral outward. It then burrows toward the tip of the twig and pupates.


4 responses to this post.

  1. Posted by Therese on December 1, 2013 at 12:15 pm

    Thanks, Teach! The second one looks like it has been trimmed. So interesting!


  2. Sometimes it seems like there are so many things trying to kill our trees that it’s a wonder we have any.


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